High octane gasoline is needed for modern gasoline engines. Previously, octane numbers were often improved by incorporating various lead-containing additives into the gasoline. As lead-containing additives have been phased out of gasoline for environmental reasons, it has become increasingly necessary to rearrange the structure of the hydrocarbons used in gasoline blending to achieve higher octane ratings. Catalytic reforming of hydrocarbons is a process widely used by refiners for upgrading the octane ratings of gasoline as well as for other useful hydrocarbon conversion applications.
In catalytic reforming, a hydrocarbon feedstock of, for example, C5 hydrocarbons to about C11 hydrocarbons, is contacted with a reforming catalyst to convert at least a portion of the heavier hydrocarbons to aromatic hydrocarbons, for example, to increase the octane content of gasoline. Invariably, the catalyst used in such processes becomes deactivated for one or more reasons including the accumulation of coke deposits on the catalyst.
Regeneration of the catalyst removes the coke deposits and helps restore the activity of the catalyst. Coke is normally removed from the catalyst by a regeneration operation that contacts the coke-containing catalyst at high temperatures with an oxygen-containing gas to combustively remove the coke. In continuous or semi-continuous catalyst regeneration processes, coke laden particles are at least periodically added and withdrawn from a bed of catalyst in a regeneration vessel in which the coke is combusted. Regions of intense burning that extend through portions of the catalyst bed develop as the coke is combusted. After this intense burning, certain catalysts require further reconditioning to restore their effectiveness. For example, reforming catalyst typically contain chloride compounds and noble metals, such as platinum. These catalysts require reconditioning to restore the activity of the noble metal to its most highly catalytic state and to replace chloride on the catalyst that may be lost in the reaction zone or through the combustion of coke. Reconditioning for a reforming catalyst generally includes contact with a chloride containing compound in a chlorination zone of the regeneration vessel, to redistribute the platinum metal and replace the chloride that may be lost from the catalyst, followed by a drying step to reduce the moisture content of the catalyst and finally a reducing step to change the platinum metal from various oxide states to a reduced metallic condition. The various steps for regenerating catalyst and for moving the catalyst around for regeneration including for reconditioning often require the introduction of heat at various points into the system, which may be supplied, for example, by steam or other source(s) that may be detrimental if it leaks into the system and contacts the catalyst and/or that may be inefficient from an overall process standpoint.
Accordingly, it is desirable to provide apparatuses and methods for catalytic reforming of hydrocarbons with improved heat management for regeneration of a catalyst. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.